1. Field of the Invention
This invention relates to a post for a press, such as a roll press couple in a papermaking machine. More particularly, this invention relates to a load-bearing post having a removable section which permits passage of a looped member, such as a papermaking machine felt, through the space vacated by the removable section between the inner and outer sides of the post. Still more particularly, this invention relates to a quick-release apparatus for a vertical post wherein the post can be quickly configured between an open position, to permit passage of a looped member through the post, to a closed position where the post becomes a rigid, load-bearing structure.
2. Description of the Prior Art
In papermaking machines, and in some other pressing equipment utilizing looped members which need to pass through the press, there is a need for a frame support structure which can both withstand the tensile stress induced in the vertical posts by the opposed pressing members pushing against one another on either side of the support structure and which can also be opened, at least on one side, to permit lateral insertion and removal of a looped or otherwise continuous member, such as a papermaking felt in the press.
In a papermaking machine press, the press members typically comprise either a pair of co-rotating rolls nipped together or a single rotating roll which bears against a so-called shoe having a concave face conforming to the cylindrical surface of the roll. In both such papermaking machine press sections, one or two water-absorbing felts and possibly a fabric or water-impervious blanket also pass through the nip between either the co-rotating rolls or the roll and shoe. The felts are disposed on one or both sides of the paper web to absorb water expressed from the paper web by the nip. The configuration using a roll nipped with a shoe is known in the papermaking industry as an extended nip, or wide nip, type press. In an extended nip type of press, a water impervious blanket also passes through the nip to provide a surface which does not move relative to the paper web or felt interposed between the blanket and paper web. The other side of the blanket is lubricated so as to facilitate its passage over the surface of the shoe which pressures the felts, paper web and blanket against the surface of the rotating roll.
In all of these papermaking press configurations, the felts and blanket are typically endless loops, which must be brought into, and out of, operating position over the face of the roll as an integral piece which requires that they be moved over the ends of the rolls or, in the case of an extended nip type of press, the shoe. This requires that a section of the press frame be removed to permit the felt, belt or blanket to be inserted without breaking its loop.
Prior such framework requires the use of a crane to hold the upper part of the frame when its removable section is removed to permit the looped felt, belt or blanket to be inserted transversely across the width of the machine in the direction of the roll axis of rotation. Such a configuration is utilized in a so-called free-standing frame for an extended nip type press.
Another prior art press frame configuration utilizes a massive, fixedly mounted overhead beam from which links hang down on which the lower press roll member is mounted. At the bottom of the parallel, downwardly extending link members, a removable base frame member is attached and spaced from the floor. The base frame member can then be supported relative to the floor and lifted slightly to permit the links to be pivoted upwardly out of the way so the looped felt or other member can be positioned in the space between the rolls forming the press couple.
In typical prior press configurations of structural framework having removable sections for permitting passage of flexible, looped web processing members into and out of the press, the removable sections are held in place by swing bolts which pivot from either side of the span of the removable section. In some prior configurations, so-called shear plates are bolted to opposed sides of a vertical post component of the framework such that one or more key-like members are held between the post and a contiguous shear plate to maintain rigidity and permit the post to be put under tension.
As the speeds and nip loads of papermaking machines increase, the tensile strength of the swing bolts and shear plate arrangements are not adequate to maintain the beam members containing the removable sections pressed together tight enough to provide the required rigidity and structural integrity to maintain the strength, alignment and resistance to vibration required during operation. In some cases, a single large so-called hydraulic bolt, which utilizes a hydraulically actuated nut, has been implanted in the press post and special retraction means are required to move the bolt to permit the removable section to be removed. In other cases, shear plates are used to carry the high tensile loads, but such shear plates require more space, are time consuming to remove and are difficult to pre-load.